Topics of current interest are: (1) The regulation of glycogen metabolism in normal placenta, choriocarcinoma, and SV40-transformed placental cells; (2) a comparison of eutopic synthesis of placental alkaline phosphatase, other placental enzymes, and human chorionic gonadotrophin by trophoblastic tumor cells with the ectopic synthesis by nontrophoblastic tumor cells; and (3) elucidation of the significance of multiple protein kinases and phosphoprotein phosphatases in the phosphorylation and dephosphorylation of glycogen synthase.